|Xia Junqiang,Liu Xin,Deng Shanshan,Zhou Meirong,Li Zhiwei,Peng Yuming.Temporal and spatial distribution of bank retreat in the Jingjiang reach of the Yangtze River after the Three Gorges Project operation and its influence on channel adjustment. J. Lake Sci.2022,34(1):296-306. DOI:10.18307/2022.0124
|关键词: 河道崩岸 崩岸土体体积 断面形态 河床调整 荆江河段 三峡工程
|Temporal and spatial distribution of bank retreat in the Jingjiang reach of the Yangtze River after the Three Gorges Project operation and its influence on channel adjustment
Xia Junqiang1, Liu Xin1, Deng Shanshan1, Zhou Meirong1, Li Zhiwei1, Peng Yuming2
1.State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, P. R. China;2.Jingjiang Bureau of Hydrology and Water Resources Survey, Changjiang Water Resources Commission, Jingzhou 434020, P. R. China
|After the operation of the Three Gorges Project, the Jingjiang reach underwent remarkable channel degradation, and bank retreat occurred frequently in local sub-reaches, which affected the transport of suspended sediment and the adjustments of channel geometry. The measured fluvial topographic maps and cross-sectional profiles during the period of 2002-2018 were adopted to determine the main zones and volumes of bank erosion, and the effect of bank retreat was then analyzed quantitatively on the channel adjustments of the Jingjiang reach. Calculated results show that:the cumulative volume of bank erosion in the Jingjiang reach was about 2.0×108 m3 during the period of 2002-2018, which accounted for 17.5% of the cumulative channel scour volume (11.4×108 m3). Empirical relationships were developed between cumulative bank erosion volume and fluvial erosion intensity during flood seasons in the Lalinzhou and Beimenkou sub-reaches, with the determination coefficients of 0.95 and 0.97 respectively. In addition, the total sediment amount from bank erosion in the Jingjiang reach was around 2.7×108 t, and the total amount in the reach between Zhicheng and Jianli was 1.67×108 t, accounting for about 30.7% of the total amount of sediment supplied from the channel. Therefore, bank retreat played an important role in the suspended sediment transport, especially for the recovery of fine sand along the channel. Finally, cross-sectional profiles tended to be wide and shallow during the stage of continuous bank retreat, while they became narrow and deep after the construction of bank revetment engineering. Therefore, bank retreat can reduce the undercutting of the riverbed to a certain extent in the Jingjiang reach.
|Key words: Bank erosion soil volume from bank erosion cross-sectional geometry channel adjustments Jingjiang reach Three Gorges Project